Publications (64)178.49 Total impact
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Article: Cerebral perfusion alterations in epileptic patients during peri-ictal and post-ictal phase: PASL vs DSC-MRI.
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ABSTRACT: Non-invasive pulsed arterial spin labeling (PASL) MRI is a method to study brain perfusion that does not require the administration of a contrast agent, which makes it a valuable diagnostic tool as it reduces cost and side effects. The purpose of the present study was to establish the viability of PASL as an alternative to dynamic susceptibility contrast (DSC-MRI) and other perfusion imaging methods in characterizing changes in perfusion patterns caused by seizures in epileptic patients. We evaluated 19 patients with PASL. Of these, the 9 affected by high-frequency seizures were observed during the peri-ictal period (within 5hours since the last seizure), while the 10 patients affected by low-frequency seizures were observed in the post-ictal period. For comparison, 17/19 patients were also evaluated with DSC-MRI and CBF/CBV. PASL imaging showed focal vascular changes, which allowed the classification of patients in three categories: 8 patients characterized by increased perfusion, 4 patients with normal perfusion and 7 patients with decreased perfusion. PASL perfusion imaging findings were comparable to those obtained by DSC-MRI. Since PASL is a) sensitive to vascular alterations induced by epileptic seizures, b) comparable to DSC-MRI for detecting perfusion asymmetries, c) potentially capable of detecting time-related perfusion changes, it can be recommended for repeated evaluations, to identify the epileptic focus, and in follow-up and/or therapy-response assessment.Magnetic Resonance Imaging 04/2013; · 1.99 Impact Factor -
Article: Subclinical Rhythmic Electroencephalogram Discharge of Adults Occurring During Sleep: A Diagnostic Challenge.
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ABSTRACT: Subclinical rhythmic electroencephalogram discharge of adults (SREDA) is an electroencephalogram (EEG) pattern of uncertain significance, which occurs without any correlation with epilepsy. It resembles epileptiform activity, and is therefore likely to be misinterpreted as an authentic epileptiform pattern. We describe the occurrence of SREDA during stage II nonrapid eye movement (NREM) sleep and discuss the diagnostic difficulties that may arise when such a pattern is encountered during sleep EEG recordings. SREDA may occur during sleep, leading to difficulties in correct identification of this pattern, as the patient is unconscious and unable to report any symptoms. Although there are rather distinctive EEG features, the lack of changes in electrocardiogram rhythm and the absence of ocular/muscular artifacts suggest a nonepileptic phenomenon. The ultimate diagnosis, and the correct identification of SREDA, may be achieved by a comparison of EEG features between the pattern occurring during sleep and that recorded in the awake state.Clinical EEG and neuroscience: official journal of the EEG and Clinical Neuroscience Society (ENCS) 03/2013; · 1.73 Impact Factor -
Article: Visual cortex hyperexcitability in idiopathic generalized epilepsies with photosensitivity: A TMS pilot study.
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ABSTRACT: BACKGROUND: The current understanding of the mechanisms underlying photosensitivity is still limited, although most studies point to a hyperexcitability of the visual cortex. METHODS: Using transcranial magnetic stimulation, we determined the resting motor threshold (rMT) and the phosphene threshold (PT) in 33 patients with IGEs (8 with photosensitivity) compared with 12 healthy controls. RESULTS: Eleven controls (92%) reported phosphenes compared with fifteen (46%) patients with idiopathic generalized epilepsy (p=0.015). Phosphenes were reported more frequently among patients with epilepsy with photosensitivity (87.5%) than in patients with active epilepsy without photosensitivity (30.8%) (p=0.038) and patients with epilepsy in remission without photosensitivity (33.3%) (p=0.054); no differences were found between patients with epilepsy with photosensitivity and controls (p=0.648). Resting motor threshold and phosphene threshold were significantly higher among patients with epilepsy (active epilepsy or epilepsy in remission without photosensitivity) compared to healthy controls (p<0.01). Conversely, patients with active epilepsy and photosensitivity had significantly lower values than controls (p=0.03). CONCLUSIONS: The marked decrease in PT and the high phosphene prevalence in patients with IGE with photosensitivity indicate a regional hyperexcitability of the primary visual cortex. Results of this study also suggest that the PT may serve as a biomarker for excitability in patients with IGE and photosensitivity.Epilepsy & Behavior 03/2013; 27(2):301-306. · 2.34 Impact Factor -
Article: Effects of prefrontal repetitive transcranial magnetic stimulation on the autonomic regulation of cardiovascular function.
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ABSTRACT: Several protocols based on repetitive transcranial magnetic stimulation (rTMS) have been proposed for treatment of a variety of neurological disorders. Despite the widespread use, little is known about the effects of rTMS on the autonomic nervous control of the cardiovascular system. Twelve volunteers underwent rTMS sessions consisted in 8-min baseline recording, 8-min 0.7-Hz rTMS stimulation at 100 % of the motor cortex excitability threshold on the prefrontal cortex of one randomly assigned hemisphere. After 8-min recovery, the same procedure was performed on the contra-lateral hemisphere. Non-invasive (Portapres device) beat-by-beat blood pressure and heart period time series were recorded and analyzed by spectral and cross-spectral analysis in the low-frequency (LF ≈ 0.1 Hz) and in the high-frequency (HF = respiratory frequency) range. Repetitive TMS, particularly after stimulation of the right hemisphere, induced a slight increase in the parasympathetic drive and no effects on the sympathetic activity. There was a significant bradycardia after stimulation on the right hemisphere, not significant bradycardia after left stimulation. LF/HF ratio was 3.8 ± 2.1 during baseline and changed to 1.9 ± 0.6 during rTMS on the left and to 1.6 ± 0.6 during rTMS on the right. No significant changes were observed in blood pressure. Low-frequency rTMS of the prefrontal cortex induces a slight parasympathetic activation and no changes in the sympathetic function.Experimental Brain Research 03/2013; · 2.39 Impact Factor -
Article: Modulation of event-related desynchronization in robot-assisted hand performance: brain oscillatory changes in active, passive and imagined movements.
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ABSTRACT: BACKGROUND: Robot-assisted therapy in patients with neurological disease is an attempt to improve function in a moderate to severe hemiparetic arm. A better understanding of cortical modifications after robot-assisted training could aid in refining rehabilitation therapy protocols for stroke patients. Modifications of cortical activity in healthy subjects were evaluated during voluntary active movement, passive robot-assisted motor movement, and motor imagery tasks performed under unimanual and bimanual protocols METHODS: Twenty-one channel electroencephalography (EEG) was recorded with a video EEG system in 8 subjects. The subjects performed robot-assisted tasks using the Bi-Manu Track robot-assisted arm trainer. The motor paradigm was executed during one-day experimental sessions under eleven unimanual and bimanual protocols of active, passive and imaged movements. The event-related-synchronization/desynchronization (ERS/ERD) approach to the EEG data was applied to investigate where movement-related decreases in alpha and beta power were localized RESULTS: Voluntary active unilateral hand movement was observed to significantly activate the contralateral side; however, bilateral activation was noted in all subjects on both the unilateral and bilateral active tasks, as well as desynchronization of alpha and beta brain oscillations during the passive robot-assisted motor tasks. During active-passive movement when the right hand drove the left one, there was predominant activation in the contralateral side. Conversely, when the left hand drove the right one, activation was bilateral, especially in the alpha range. Finally, significant contralateral EEG desynchronization was observed during the unilateral task and bilateral ERD during the bimanual task CONCLUSIONS: This study suggests new perspectives for the assessment of patients with neurological disease. The findings may be relevant for defining a baseline for future studies investigating the neural correlates of behavioral changes after robot-assisted training in stroke patients.Journal of NeuroEngineering and Rehabilitation 02/2013; 10(1):24. · 3.26 Impact Factor -
Article: Clinical utility of ictal eyes closure in the differential diagnosis between epileptic seizures and psychogenic events.
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ABSTRACT: The presence of ictal eye closure (IEC) has been considered to represent an additional clinical sign supporting the diagnosis of psychogenic non-epileptic events (PNEEs). We undertook a systematic review to evaluate sensitivity, specificity and likelihood ratios (LR) of IEC in the differential diagnosis between PNEEs and epileptic seizures. Six studies (total of 1496 events; 1021 epileptic seizures and 475 PNEEs) were included. Pooled accuracy measures of IEC for the diagnosis of PNEE were: sensitivity 58% (0.579) (95% CI 0.534-0.623), specificity 80% (0.895) (95% 0.875-0.9131)%, pLR 5.524 (95% CI 4.546-6.714) and nLR 0.47 (95% CI 0.422-0.524). However, a sensitivity analysis including only the studies performing an IEC assessment blinded to the diagnoses yielded results indicative of a rather low diagnostic value of IEC (pLR 3.056) compared with the analysis including unblinded studies (pLR 12.754). Further studies evaluating the occurrence of IEC through direct observation by means of video-EEG recording and blind to both EEG tracings and patient diagnosis are therefore required to definitely estimate the diagnostic utility of this sign in the differential diagnosis between epileptic seizures and PNEEs.Epilepsy research 01/2013; · 2.48 Impact Factor -
Article: Frequency and time-frequency analysis of intraoperative ECoG during awake brain stimulation.
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ABSTRACT: Electrocortical stimulation remains the standard for functional brain mapping of eloquent areas to prevent postoperative functional deficits. The aim of this study was to investigate whether the short-train technique (monopolar stimulation) and Penfield's technique (bipolar stimulation) would induce different effects on brain oscillatory activity in awake patients, as quantified by electrocorticography (ECoG). The study population was seven patients undergoing brain tumor surgery. Intraoperative bipolar and monopolar electrical stimulation for cortical mapping was performed during awake surgery. ECoG was recorded using 1 × 8 electrode strip. Spectral estimation was calculated using a parametric approach based on an autoregressive model. Wavelet-based time-frequency analysis was then applied to evaluate the temporal evolution of brain oscillatory activity. Both monopolar and bipolar stimulation produced an increment in delta and a decrease in beta powers for the motor and the sensory channels. These phenomena lasted about 4 s. Comparison between monopolar and bipolar stimulation showed no significant difference in brain activity. Given the importance of quantitative signal analysis for evaluating response accuracy, ECoG recording during electrical stimulation is necessary to characterize the dynamic processes underlying changes in cortical responses in vivo. This study is a preliminary approach to the quantitative analysis of post-stimulation ECoG signals.Frontiers in Neuroengineering 01/2013; 6:1. -
Article: Primary visual cortex excitability in migraine: a systematic review with meta-analysis.
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ABSTRACT: The objective is to update and extend previous results of a systematic review of the literature with meta-analysis performed to determine the prevalence of phosphenes and the phosphene threshold (PT) values obtained during single-pulse transcranial magnetic stimulation (TMS) in adults with migraine. Both published and unpublished controlled studies measuring PT by single-pulse TMS in adults with migraine with or without aura (MA, MwA) were systematically reviewed. Prevalence of phosphenes and PT values were assessed calculating mean difference (MD) and odds ratio (OR) with 95 % confidence intervals (CI). Fifteen trials (369 migraine patients and 269 controls), were included. Patients with MA had a statistically significant lower PT compared with controls when a circular coil was used (MD: -22.27, 95 % CI -33.44 to -11.10); with a figure-of-eight coil the difference was not statistically significant. There was a significant higher phosphene prevalence in MA compared with controls (OR: 3.57, 95 % CI 1.16-10.94). No significant differences were found either in phosphene reporting between patients with MwA and controls, or in PT values obtained by figure-of-eight coil in subjects with MwA versus controls. In general, these results slightly support the hypothesis of a primary visual cortex hyper-excitability in MA, providing not enough evidence for MwA. A significant heterogeneity across studies probably reflects relevant clinical and methodological heterogeneity.Neurological Sciences 12/2012; · 1.32 Impact Factor -
Article: The diagnostic value of urinary incontinence in the differential diagnosis of seizures.
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ABSTRACT: PURPOSE: Urinary incontinence may occur both in epileptic seizures (ES) and in non-epileptic events (NEE) such as psychogenic nonepileptic events (PNEEs) and syncope. A comprehensive search of the literature to determine the accuracy of this physical finding and its prevalence in epileptic seizures and syncope is still lacking. To undertake a systematic review to determine sensitivity, specificity and likelihood ratios (LR) of urinary incontinence in the differential diagnosis between ES and NEEs (including syncope and PNEEs). METHODS: Studies evaluating the presence of urinary incontinence in ES and NEEs were systematically searched. Sensitivity, specificity, positive and negative likelihood ratio (pLR, nLR) of incontinence were determined for each study and for the pooled results. RESULTS: Five studies (221 epilepsy patients and 252 subjects with NEEs) were included. Pooled accuracy measures of urinary incontinence (ES versus NEEs) were: sensitivity 38%, specificity 57%, pLR 0.879 (95% CI 0.705-1.095) and nLR 1.092 (95% CI 0.941-1.268). For each comparison (epileptic seizures versus NEEs; ES versus syncope; ES versus PNEEs), pooled accuracy measures for urinary incontinence showed a statistically not significant pLR (the 95% CI of the pooled value included 1, and the LR value of 1 has no discriminatory value). CONCLUSIONS: A pooled analysis of data from the literature shows that urinary incontinence has no value either in the differential diagnostic between ES and syncope/PNEEs. Systematic reviews with pooled analyses of data from the literature allow an increase in statistical power and an improvement in precision, representing a useful tool to determine the accuracy of a certain physical finding in the differential diagnosis between ES and other paroxysmal events.Seizure 11/2012; · 1.80 Impact Factor -
Article: A multimodal imaging approach to the evaluation of post-traumatic epilepsy.
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ABSTRACT: Electroencephalography-functional magnetic resonance imaging (EEG-fMRI) coregistration and high-density EEG (hdEEG) can be combined to map noninvasively abnormal brain activation elicited by epileptic processes. By combining noninvasive imaging techniques in a multimodal approach, we sought to investigate pathophysiological mechanisms underlying epileptic activity in seven patients with severe traumatic brain injury. Standard EEG and fMRI data were acquired during a single scanning session. The EEG-fMRI data were analyzed using the general linear model and independent component analysis. Source localization of interictal epileptiform discharges (IEDs) was performed using 256-channel hdEEG. Blood oxygenation level dependent (BOLD) localizations were then compared to EEG source reconstruction. On hdEEG, focal source localization was detected in all seven patients; in six out of seven it was concordant with the expected epileptic activity as defined by EEG data and clinical evaluation; and in four out of seven in whom IEDs were recorded, BOLD signal changes were observed. These activities were partially concordant with the source localization. Multimodal integration of EEG-fMRI and hdEEG combining two different methods to localize the same epileptic foci appears to be a promising tool to noninvasively map abnormal brain activation in patients with post-traumatic brain injury.MAGMA Magnetic Resonance Materials in Physics Biology and Medicine 05/2012; 25(5):345-60. · 1.88 Impact Factor -
Article: Transcranial magnetic stimulation of visual cortex in migraine patients: a systematic review with meta-analysis.
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ABSTRACT: We systematically reviewed the literature to evaluate the prevalence of phosphenes and the phosphene threshold (PT) values obtained during single-pulse transcranial magnetic stimulation (TMS) in adults with migraine. Controlled studies measuring PT by single-pulse TMS in adults with migraine with or without aura (MA, MwA) were systematically searched. Prevalence of phosphenes and PT values were assessed calculating mean difference (MD) and odds ratio (OR) with 95 % confidence intervals (CI). Ten trials (277 migraine patients and 193 controls) were included. Patients with MA had statistically significant lower PT compared with controls when a circular coil was used (MD -28.33; 95 % CI -36.09 to -20.58); a similar result was found in MwA patients (MD -17.12; 95 % CI -23.81 to -10.43); using a figure-of-eight coil the difference was not statistically significant. There was a significantly higher phosphene prevalence in MA patients compared with control subjects (OR 4.21; 95 % CI 1.18-15.01). No significant differences were found either in phosphene reporting between patients with MwA and controls, or in PT values obtained with a figure-of-eight coil in MA and MwA patients versus controls. Overall considered, these results support the hypothesis of a primary visual cortex hyper-excitability in MA, providing not enough evidence for MwA. A significant statistical heterogeneity reflects clinical and methodological differences across studies, and higher temporal variabilities among PT measurements over time, related to unstable excitability levels. Patients should therefore be evaluated in the true interictal period with an adequate headache-free interval. Furthermore, skull thickness and ovarian cycle should be assessed as possible confounding variables, and sham stimulation should be performed to reduce the rate of false positives. Phosphene prevalence alone cannot be considered a measure of cortical excitability, but should be integrated with PT evaluation.The Journal of Headache and Pain 04/2012; 13(5):339-49. · 2.43 Impact Factor -
Article: Resting motor threshold in idiopathic generalized epilepsies: a systematic review with meta-analysis.
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ABSTRACT: Resting motor threshold (rMT) assessed by means of Transcranial Magnetic Stimulation (TMS) is thought to reflect trans-synaptic excitability of cortico-spinal neurons. TMS studies reporting rMT in idiopathic generalized epilepsies (IGEs) yielded discrepant results, so that it is difficult to draw a definitive conclusion on cortico-spinal excitability in IGEs by simple summation of previous results regarding this measure. Our purpose was to carry out a systematic review and a meta-analysis of studies evaluating rMT values obtained during single-pulse TMS in patients with IGEs. Controlled studies measuring rMT by single-pulse TMS in drug-naive patients older than 12 years affected by IGEs were systematically reviewed. rMT values were assessed calculating mean difference and odds ratio with 95% confidence intervals (CI). Fourteen trials (265 epileptic patients and 424 controls) were included. Patients with juvenile myoclonic epilepsy (JME) have a statistically significant lower rMT compared with controls (mean difference: -6.78; 95% CI -10.55 to -3.00); when considering all subtypes of IGEs and IGEs other than JME no statistically significant differences were found. Overall considered, the results are indicative of a cortico-spinal hyper-excitability in JME, providing not enough evidence for motor hyper-excitability in other subtypes of IGE. The considerable variability across studies probably reflects the presence of relevant clinical and methodological heterogeneity, and higher temporal variability among rMT measurements over time, related to unstable cortical excitability in these patients.Epilepsy research 04/2012; 101(1-2):3-13. · 2.48 Impact Factor -
Article: The gating role of the thalamus to protect sleep: an f-MRI report.
Sleep Medicine 03/2012; 13(4):447-9. · 3.40 Impact Factor -
Article: Time-frequency analysis of short-lasting modulation of EEG induced by intracortical and transcallosal paired TMS over motor areas.
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ABSTRACT: Dynamic changes in spontaneous electroencephalogram (EEG) rhythms can be seen to occur with a high rate of variability. An innovative method to study brain function is by triggering oscillatory brain activity with transcranial magnetic stimulation (TMS). EEG-TMS coregistration was performed on five healthy subjects during a 1-day experimental session that involved four steps: baseline acquisition, unconditioned single-pulse TMS, intracortical inhibition (ICI, 3 ms) paired-pulse TMS, and transcallosal stimulation over left and right primary motor cortex (M1). A time-frequency analysis based on the wavelet method was used to characterize rapid modifications of oscillatory EEG rhythms induced by TMS. Single, paired, and transcallosal TMS applied on the sensorimotor areas induced rapid desynchronization over the frontal and central-parietal electrodes mainly in the alpha and beta bands, followed by a rebound of synchronization, and rapid synchronization of delta and theta activity. Wavelet analysis after a perturbation approach is a novel way to investigate modulation of oscillatory brain activity. The main findings are consistent with the concept that the human motor system may be based on networklike oscillatory cortical activity and might be modulated by single, paired, and transcallosal magnetic pulses applied to M1, suggesting a phenomenon of fast brain activity resetting and triggering of slow activity.Journal of Neurophysiology 02/2012; 107(9):2475-84. · 3.32 Impact Factor -
Article: Long lasting modulation of cortical oscillations after continuous theta burst transcranial magnetic stimulation.
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ABSTRACT: Transcranial magnetic theta burst stimulation (TBS) differs from other high-frequency rTMS protocols because it induces plastic changes up to an hour despite lower stimulus intensity and shorter duration of stimulation. However, the effects of TBS on neuronal oscillations remain unclear. In this study, we used electroencephalography (EEG) to investigate changes of neuronal oscillations after continuous TBS (cTBS), the protocol that emulates long-term depression (LTD) form of synaptic plasticity. We randomly divided 26 healthy humans into two groups receiving either Active or Sham cTBS as control over the left primary motor cortex (M1). Post-cTBS aftereffects were assessed with behavioural measurements at rest using motor evoked potentials (MEPs) and at active state during the execution of a choice reaction time (RT) task in combination with continuous electrophysiological recordings. The cTBS-induced EEG oscillations were assessed using event-related power (ERPow), which reflected regional oscillatory activity of neural assemblies of θ (4-7.5 Hz), low α (8-9.5 Hz), µ (10-12.5 Hz), low β (13-19.5 Hz), and high β (20-30 Hz) brain rhythms. Results revealed 20-min suppression of MEPs and at least 30-min increase of ERPow modulation, suggesting that besides MEPs, EEG has the potential to provide an accurate cortical readout to assess cortical excitability and to investigate the interference of cortical oscillations in the human brain post-cTBS. We also observed a predominant modulation of β frequency band, supporting the hypothesis that cTBS acts more on cortical level. Theta oscillations were also modulated during rest implying the involvement of independent cortical theta generators over the motor network post cTBS. This work provided more insights into the underlying mechanisms of cTBS, providing a possible link between synchronised neural oscillations and LTD in humans.PLoS ONE 01/2012; 7(4):e35080. · 4.09 Impact Factor -
Article: Coexistence of two distinct benign EEG variants in the same subject.
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ABSTRACT: Rhythmic temporal theta bursts of drowsiness (RTTD), also known as "psychomotor variant", and subclinical rhythmic EEG discharge of adults (SREDA) are two EEG patterns of uncertain significance that occur without any correlation with epilepsy. Each of these patterns has been described to occur alone and in the literature there are no previous reports of co-occurrence of the two distinct benign EEG variants in the same patient. We describe the coexistence of RTTD and SREDA in EEG recordings from the same subject. Although the coexistence of two distinct EEG variants in the same patient is a rarity, these patterns are not so infrequently encountered when present alone and should thus be promptly recognised in order to avoid misdiagnosis of epilepsy due to an over-interpretation of normal sharp patterns.Epileptic disorders: international epilepsy journal with videotape 12/2011; 13(4):441-5. · 1.50 Impact Factor -
Article: Unilateral fixed mydriasis: an uncommon presentation of temporal lobe epilepsy.
Journal of Neurology 07/2011; 259(2):355-7. · 3.47 Impact Factor -
Article: The sleep-deprived brain in normals and patients with juvenile myoclonic epilepsy: a perturbational approach to measuring cortical reactivity.
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ABSTRACT: Simultaneous electroencephalography-transcranial magnetic stimulation (EEG-TMS) investigates cortical reactivity to external perturbations. TMS evoked potentials (TEPs) have been described in normals during sleep and wake but not after sleep deprivation or in pathologically enhanced excitability, i.e., epilepsy. The aim of our study was to identify TEPs and their modifications via EEG-TMS co-registration in healthy controls and patients with juvenile myoclonic epilepsy (JME) during wake, sleep deprivation and sleep conditions. Focal TMS was administered to the primary motor cortex in 12 healthy controls and 10 patients with JME. At least 150 TMS were delivered randomly every 8-15s during wake, sleep deprivation and sleep conditions. EEG was simultaneously acquired from 32 scalp electrodes. A significant increase in late peak amplitudes (P100 and N190) was observed in all subjects during the sleep-deprived condition, with a marked anterior increase and overall higher amplitude potentials in the JME patients. We demonstrated an overall higher cortical excitability in the JME patients, particularly over the anterior cortex after sleep deprivation and rebound sleep. This phenomenon could be related to the cortico-thalamic circuit dysfunctions believed to cause myoclonic epilepsy and a higher susceptibility of the frontal and prefrontal areas to the effects of sleep deprivation.Epilepsy research 07/2011; 96(1-2):123-31. · 2.48 Impact Factor -
Article: Infliximab-related seizures: a first case study.
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ABSTRACT: Seizures following infliximab treatment are very rare and, to date, there is no detailed description of EEG abnormalities with cerebral radiological findings reported in cases with infliximab-related seizures. We describe a patient who acutely developed seizures temporally related to infliximab treatment, which disappeared after drug withdrawal. MRI showed encephalopathy involving mainly cortical regions and EEGs showed focal paroxysmal activity which completely disappeared a few days after infliximab withdrawal. No other plausible cause of the seizures was identified. The clear temporal association between seizure onset and infliximab treatment as well as the clinical improvement and disappearance of focal epileptiform activity after drug withdrawal indicated an evident correlation between seizures and infliximab therapy. The coexistence of pathological findings on MRI suggested that seizures were secondary to the encephalopathy. Further studies are required to evaluate whether infliximab per se has an epileptogenic effect or whether the seizures are caused by encephalopathy involving cortico-subcortical regions.Epileptic disorders: international epilepsy journal with videotape 06/2011; 13(2):214-7. · 1.50 Impact Factor -
Article: Integrating EEG and fMRI in epilepsy.
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ABSTRACT: Integrating electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) studies enables to non-invasively investigate human brain function and to find the direct correlation of these two important measures of brain activity. Presurgical evaluation of patients with epilepsy is one of the areas where EEG and fMRI integration has considerable clinical relevance for localizing the brain regions generating interictal epileptiform activity. The conventional analysis of EEG-fMRI data is based on the visual identification of the interictal epileptiform discharges (IEDs) on scalp EEG. The convolution of these EEG events, represented as stick functions, with a model of the fMRI response, i.e. the hemodynamic response function, provides the regressor for general linear model (GLM) analysis of fMRI data. However, the conventional analysis is not automatic and suffers of some subjectivity in IEDs classification. Here, we present an easy-to-use and automatic approach for combined EEG-fMRI analysis able to improve IEDs identification based on Independent Component Analysis and wavelet analysis. EEG signal due to IED is reconstructed and its wavelet power is used as a regressor in GLM. The method was validated on simulated data and then applied on real data set consisting of 2 normal subjects and 5 patients with partial epilepsy. In all continuous EEG-fMRI recording sessions a good quality EEG was obtained allowing the detection of spontaneous IEDs and the analysis of the related BOLD activation. The main clinical finding in EEG-fMRI studies of patients with partial epilepsy is that focal interictal slow-wave activity was invariably associated with increased focal BOLD responses in a spatially related brain area. Our study extends current knowledge on epileptic foci localization and confirms previous reports suggesting that BOLD activation associated with slow activity might have a role in localizing the epileptogenic region even in the absence of clear interictal spikes.NeuroImage 02/2011; 54(4):2719-31. · 5.89 Impact Factor
Top co-authors
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Institutions
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2013
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Azienda Ospedaliera Universitaria Integrata Verona
- Division of Neurology
Verona, Veneto, Italy
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1995–2013
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Università degli studi di Verona
- • Section of Neurology
- • Department of Neurological, Neuropsychological, Morphological and Movement Sciences
- • Section of Urology
- • Department of Neurological and Visual Sciences
Verona, Veneto, Italy
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2012
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University of Leicester
- School of Psychology
Leicester, ENG, United Kingdom
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2010
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University Hospital San Martino
Genova, Liguria, Italy -
IRCCS Centro San Giovanni di Dio, Fatebenefratelli, Brescia
Brescia, Lombardy, Italy
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